WASM examples (+ backports of new official examples) (#344)

* chg: New build system that uses the officially distributed binaries, bumped version to 8.0.0, simplified git workflow, removed deprecated OpenGL 1.1 functionality.

* chg: Modernize CI workflow, enable SourceLink

- Bump workflow actions to latest majors (Node 24); drop deprecated softprops/action-gh-release@v1
- Trigger push builds on main instead of master
- Create local nuget feed dir before pack (fixes NU1301)
- Enable Microsoft.SourceLink.GitHub for debugging symbols (ref PR #340)

* fix: centralized version data in Directory.build.props, and fixed various interop details that had incorrect function signatures

* chore: updated readme

* fix: version the native extract marker and chain download via DependsOnTargets

The .extracted marker now includes the raylib package name, so bumping
TargetRaylibTag re-extracts the new archive instead of silently keeping
(and packing/copying) the previous version's files.

_PrepareNativeLibrary and _StageWasmNative now depend directly on
_DownloadAndExtractInternal instead of CallTarget-ing it; dependency
targets run in the same project instance, so the resolved properties
(RaylibPackageName etc.) propagate naturally.

* fix: let the binding build for browser-wasm on both net8.0 and net10.0

The net8-era wasm workload (Microsoft.NET.Runtime.WebAssembly.Sdk 8.0.x,
auto-imported for RID browser-wasm) treats every browser-wasm project as
a wasm app: it forces OutputType=Exe after project evaluation (CS5001
for a classlib) and hooks its app-bundle build after Build, which errors
because a library has no assemblies to bundle. Opt Raylib-cs out via
DisableAutoWasmBuildApp (props time, before the workload defaults its
trigger) and pin OutputType back to Library in Directory.Build.targets
(evaluated after the workload props, so the assignment wins). net10's
wasm SDK needs neither workaround.

* chore: readme updated

* chg: simplifying build logic - a simple line in the documentation should save us the code here

* fix: Wrong signature of FrameBufferComplete

* chore: readme update

* feat: samples default to local project reference, and can optionally use the nuget package

* feat: backporting existing raylib-cs examples and new official raylib examples to WASM, adopting raylib's original code style

* chore: readme, gitignore, and targets backport.

* fix: Examples.csproj runs the download task when building locally

* feat: backporting existing raylib-cs examples and new official raylib examples to WASM, adopting raylib's original code style

* chore: readme, gitignore, and targets backport.

* chore: clean up linter warnings

* feat: html harness focuses the example and allows quick navigation with J/K instead.

* chore: readme mentions the property to use nuget vs. the local project reference

* feat: replaced the J/K navigation with good old HTML buttons

* chore: run dotnet format scoped default (was previously scoped to just 'style')

Examples/IExample.cs

@@ -0,0 +1,61 @@
+namespace Examples;
+
+/// <summary>
+/// A runnable raylib example. Loop-spanning state lives in instance fields, (re)initialized in
+/// <see cref="Init"/> so re-selecting an example resets it.
+///
+/// <para>
+/// Desktop drives examples via <c>Program.cs</c> (each also keeps a thin standalone
+/// <c>static Main()</c>); in the browser, <c>Web/Host.cs</c> owns the single window and calls
+/// <see cref="Update"/> one frame at a time from JavaScript. Platform divergences are guarded
+/// with <c>#if BROWSER</c>, preferably around a single constant.
+/// </para>
+/// </summary>
+public interface IExample
+{
+    /// <summary>Display name shown in the navigation dropdown.</summary>
+    string Name
+    {
+        get;
+    }
+
+    /// <summary>Window title, matching the example's standalone <c>Main()</c>.</summary>
+    string Title
+    {
+        get;
+    }
+
+    /// <summary>Desktop window size, matching the standalone <c>Main()</c>. The browser canvas is fixed at 800x450.</summary>
+    int Width => 800;
+
+    /// <inheritdoc cref="Width"/>
+    int Height => 450;
+
+    /// <summary>Config flags the desktop runner applies before window creation. Ignored in the browser.</summary>
+    ConfigFlags ConfigFlags => 0;
+
+    /// <summary>Target FPS. The desktop runner always applies it; the browser host paces its frame loop with it.</summary>
+    int TargetFps => 60;
+
+    /// <summary>Whether the desktop runner disables the cursor. Ignored in the browser (the pointer stays visible).</summary>
+    bool CursorDisabled => false;
+
+    /// <summary>Whether the desktop runner hides the cursor. Ignored in the browser.</summary>
+    bool CursorHidden => false;
+
+    /// <summary>
+    /// Whether the desktop runner should exit its frame loop; defaults to
+    /// <see cref="Raylib.WindowShouldClose"/>. Examples that intercept the close request
+    /// override this and poll WindowShouldClose in <see cref="Update"/> themselves.
+    /// </summary>
+    bool ShouldClose => WindowShouldClose();
+
+    /// <summary>Set up the Example and preload necessary resources.</summary>
+    void Init();
+
+    /// <summary>Render one frame, including BeginDrawing/EndDrawing.</summary>
+    void Update();
+
+    /// <summary>Free resources.</summary>
+    void Unload();
+}